1. Field of the Invention
This invention relates generally to a magnetic writer, referred to herein also as a write head, for a magnetic disk drive and to a method of making the head and more particularly, to a write head with a textured pole surface to increase magnon-magnon scattering.
2. Background Information
Developments in magnetic disk drives are generally aimed at increasing the bit density on the disks and, derivatively, increasing the speed of data retrieval. The write heads used to imprint the magnetic bits on the disks are subject to much of the development effort. The heads are made of a soft magnetic material, which ideally, rapidly applies a strong magnetic field to a small area on the disk in conjunction with the switching of the write current to the head.
In order to magnetize as small an area on the disk as possible, the magnetizing field at the tip of the head facing the disk should rise very quickly to its maximum level when the magnetizing current is switched to write to the disk. However, there is a delay resulting from the propagation of magnons, also termed “spin waves.” The accumulation of lightly damped spin waves leads to an effective increase in the temperature of the spins that degrades the ferromagnetism of the poles. This can reduce the saturation magnetization and increase transition time.
A known technique to dampen spin waves, and thus, mitigate this effect is to make small additions of rare earth elements, such as Praseodymium, Neodymium, Promethium, Sumarium, Europium, Gadolinium, Terbium, Dysprosium, Holium, Erbium, Thulium, Ytterbium, and Lutetium to the poles, as described in W. Bailey et al., IEEE TransMagn, Col. 37, No. 4, pp. 1748-1754, July 2001. However, sufficient inclusion of to these rare earth elements to provide the desired spin wave damping is accompanied by degradation of the soft magnetic properties of the poles, which leads to increased coercivity, reduced permeability, reduced saturation magnetization and increased magneto striction. They also increase the susceptibility of the poles to corrosion.
The present invention is directed to the damping of the spin waves without requiring the use of excessive amounts of the rare earth elements.